Many packaging applications, especially food packaging, require or benefit from the use of bags made from various thermoplastic materials and structures.
These bags are commonly used in large scale meat processing and/or packaging systems where production speed and efficiency are important. Bags to be used in these systems can be provided in various forms. For example, bags can be supplied in the form of a box of taped bags, the bags disposed on the tapes in an imbricated (shingled) arrangement. Alternatively, the bags can be supplied on a roll, with adjoining bags connected by a transverse line of serrations or perforations. In another alternative, the bags can be made from plastic tubing, converted into bags on demand.
At the loading station of a conventional bag loading system, each bag can be opened and then loaded with an article such as a fresh red meat subprimal or smoked and processed meat, poultry, cheese, or other perishable food product, or other product. This process can be done manually or mechanically.
Bags, in particular those intended for use in packaging fresh red meat subprimals and the like, are supplied to the processor in a variety of bag widths, in order to accommodate the variety of meat cuts. Currently, bag loading systems for this segment of the food processing industry are typically capable of handling only one bag size at a time. To accommodate a different meat cut, of different size, it is desirable to switch to a different bag width. This however often involves costly downtime for retooling. To be sure, a currently commercial bag loading system marketed by Cryovac as the BL 145 bag loading system does handle more than one bag width, but with significant limitations on the variability in bag widths that can be conveniently handled by the system.
Also, for a given product, it is desirable to minimize the chosen bag size needed (i.e. typically bag width) to achieve packaging efficiency and reduce cost. For example, loading a round product in a square opening requires greater bag width (and concomitantly higher cost) than loading the same round product in an optimally sized round opening.
It is therefore desirable to provide an apparatus and method for opening a bag, including an apparatus and method for holding the open bag in an open condition during loading of the bag with a product, which apparatus and method provide one or more of the following capabilities:    sequentially loading bags having a wide variety of bag widths on a single loading device without any substantial adjustment of or change in the apparatus.    configuring the apparatus to form a wide variety of bag opening shapes (i.e. bag mouths that upon opening having a cross-sectional geometry that is e.g. round, oval, half round, half oval, square, rectangular, pentagonal, hexagonal, triangular, etc.), thus providing a method of mini-mining the bag width required to package a particular product.    controlling the movement of a plurality of fingers with a single control axis which synchronizes the motion of all the fingers and minimizes the cost of the required controls.    controllably tensioning the bag opening over the full range of bag width with little or no additional mechanisms or sensors required. This feature is advantageous because in use, excessive tension should not applied to the bag opening. This could stress the material from which the bag is made beyond its yield point. The apparatus of the invention should ensure that an appropriate level of tension is applied to hold the bag in place throughout the loading operation. On the one hand, a minimal tension is required in order to avoid bag slippage during loading of a product into the bag. On the other hand, the tension should not be so high that damage to the bag occurs during the opening and loading steps.    minimizing material consumption when packaging products of variable size by selecting a given bag and adjusting the geometry of the bag opening.    including a contamination guard in the sealing zone of the bag opening to reduce or eliminate contamination of the seal area during the loading process. This is useful when loading a wet protein product like pork, beef or poultry into a bag.    including supplemental stretching fingers which move in a single axis to stretch the bag mouth for presentation of the bag to a sealing mechanism without any pleats.